A provocative new study discovers a strong relationship between maternal obesity and diabetes, and the likelihood of having a child with autism or another developmental disability.
University of California - Davis researchers found that mothers who were obese were 1-2/3 times more likely to have a child with autism as normal-weight mothers without diabetes or hypertension, and were more than twice as likely to have a child with another developmental disorder.
Furthermore, mothers with diabetes were found to have nearly 2-1/3 times the chance of having a child with developmental delays as healthy mothers.
Mothers with diabetes also had a higher risk of having a child with autism although the relationship was not statistically significant.
Researchers determined that autistic children of diabetic mothers were more disabled and had greater deficits in language comprehension and production and adaptive communication than were the children with autism born to healthy mothers.
Non-autistic children of diabetic mothers also were at risk to develop problems with socialization and language comprehension when compared with the non-autistic children of healthy women.
Maternal metabolic conditions increased the risk of mild deficits in problem-solving, language comprehension and production, motor skills and socialization among children without autism.
Diagnoses of obesity, maternal diabetes, autism and developmental disorders have increased significantly over the past three decades. The current study is the first to examine the associations between neurodevelopmental disorders and maternal metabolic conditions not restricted solely to type 2 or gestational diabetes.
“Over a third of U.S. women in their childbearing years are obese and nearly one-tenth have gestational or type 2 diabetes during pregnancy. Our finding that these maternal conditions may be linked with neurodevelopmental problems in children raises concerns and therefore may have serious public-health implications,” said biostatician Paula Krakowiak.
The study is published online in the journal Pediatrics.
The study included 1,004 mother/child pairs from diverse backgrounds enrolled in the Childhood Autism Risks from Genetics and the Environment Study (CHARGE), most of them living in Northern California, with a small subset living in Los Angeles.
The children were between 24 and 60 months old, born in California and resided with at least one biological parent who spoke either English or Spanish. There were 517 children who had autism; 172 with other developmental disorders; and 315 were developing normally. The participants were enrolled between January 2003 and June 2010.
The researchers obtained demographic and medical information for the mothers and their children using the CHARGE Study Environmental Exposure Questionnaire, a telephone survey, the study participants’ birth files and medical records. The primary metabolic conditions of interest were type 2 diabetes or gestational diabetes.
Among children whose mothers were diabetic during their pregnancies, the study found that the percentage of children with autism born to women with type 2 diabetes or gestational diabetes – 9.3 percent – or developmental disability – 11.6 percent – was higher than the 6.4 percent of children born to women without these metabolic conditions.
Over 20 percent of the mothers of children with autism or other developmental disability were obese, compared with 14 percent of the mothers of normally developing children.
Approximately 29 percent of the children with autism had mothers with a metabolic condition, and nearly 35 percent of the children with another developmental disorder had mothers with metabolic conditions, compared with 19 percent of the normal children who had mothers with a metabolic condition.
Analyses of the children’s cognitive abilities found that, among the children with autism, children of mothers with diabetes exhibited poorer performance on tests of expressive and receptive language and communication skills of everyday living when compared with the children of non-diabetic mothers. And the presence of any metabolic condition was associated with lower scores on all of the tests among children without autism.
Researchers believe that in diabetic, and possibility pre-diabetic pregnancies, poorly regulated maternal glucose can result in prolonged fetal exposure to elevated maternal glucose levels, which raises fetal insulin production resulting in chronic fetal exposure to high levels of insulin.
Because elevated insulin production requires greater oxygen use this may result in depleted oxygen supply for the fetus. Diabetes also may result in fetal iron deficiency. Both conditions can adversely affect fetal brain development, the authors said.
“The sequence of events related to poorly regulated maternal glucose levels is one potential biological mechanism that may play a role in adverse fetal development in the presence of maternal metabolic conditions,” Krakowiak said.
Maternal inflammation, which accompanies metabolic conditions, may also adversely affect fetal development. Certain proteins involved in cell signaling that are produced by cells of the immune system can cross the placenta from the mother to the fetus and disturb brain development.
Accordingly, the link between obesity and diabetes and autism and other developmental disorders is plausible although additional studies are needed to prove a cause and effect relationship.